---
tags:
  - science/physics
  - phenomena
  - sound
  - acoustics
created: 2026-05-16
breadcrumb: "Physics > Natural phenomena > Sound"
---

# Sound

> **Mechanism:** Mechanical longitudinal wave in matter

## Items

- **Pressure wave** — Sound is a compression / rarefaction wave; needs a medium.
- **Speed** — ≈ 343 m/s in air at 20 °C; ≈ 1480 m/s in water; ≈ 5100 m/s in steel.
- **Frequency** — Pitch perception: 20 Hz → 20 kHz for humans.
- **Doppler effect** — Frequency shifts with relative motion between source and observer.
- **Standing waves** — Resonance in pipes, strings, rooms; basis of musical instruments.

## Related

- [[acceleration]]